Ford 2000 3 cyl gas fuel issues

HELP!!!! My tractor is killin' me. The bowl/seperator fills and then it wants to go down half way and causes the tractor to spit, sputter and cut-off. I have blown the lines clean, replaced the fuel pump, cleaned the separator, installed new stop-cock in fuel tank. I do not know what else to do and I have a huge storm heading my way tomorrow afternoon and have about 40 rows of plasti-mulch to lay yet. PLEASE HELP!!!!